Wednesday, April 1, 2009

For the past three years I have been studying and writing about the origin of my Cooley ancestors. Three previous papers that I have written about that subject can be found in this Cooley History blog. Those three papers indicated that my ancestor, Benjamin Cooley, who migrated to Springfield, Massachusetts about 1640, probably came from the Hertfordshire area of England that is just north of London. The only specific documentation of that was a church record in the town of Tring, which showed that a Benjamin Cooley was baptized there in 1617. But thanks to a two volume work, The Cooley Genealogy by M. E. Cooley, published in 1941, we have comprehensive records of many of us who descended from Benjamin.

I concluded that if we could find some members of the Cooley family who remained in that area of England, and if we could get them to submit a sample of their saliva for DNA testing, we might be able to find a match to the DNA profile that has been established for those of us who are known descendents of Benjamin Cooley. Finding such English Cooleys was a more difficult task than I thought, but it was made easier by the Internet. I eventually found Peter Cooley willing and able to participate. His ancestors go back to the Tring area (more on that below). His DNA results are now available from EthnoAncestry, a DNA lab in the British Isles.

In using DNA in genealogical studies there are several important concepts. An analysis of the male Y chromosome reveals markers (the number of repeated sequences at specific locations on that long chromosome) which are inherited from father to son. These are known as Short Tandem Repeats (STR). Over time and many generations, the number of repeats can change due to mutations in the human genome. The set of repeat values that is obtained for a set of Y-chromosome markers is called a haplotype. Several descendents of Benjamin Cooley have had their DNA tested. This has yielded a modal haplotype for this Cooley family, where modal is simply the most frequent value for each of the markers studied. The marker values for this Cooley family group are strikingly similar. In terms of DNA alone, one could conclude that this group of Cooleys has a common ancestor. But we knew that, it was Benjamin.

Haplotypes for different individuals or groups of people can be compared and any differences in their marker values define the genetic distance between them. Close male relatives have the same haplotype and their genetic distance is zero. More distantly related people will differ on a few markers, while unrelated people will exhibit a very different haplotype.

Another important concept in genetic genealogy is haplogroup, which represents a group people related by descent based upon another kind of mutation that can occur in DNA over time. Those mutations are known as single nucleotide polymorphisms (SNP) and haplogroup classifications are based upon SNP’s. Studies of haplogroups have been the basis for the mapping of human migrations over time. Because it is easier to analyze DNA to establish ones haplotype, statistical methods have been developed to predict ones haplogroup from STR markers. The Cooley haplotype is known to be in haplogroup R1b. The first thing that EthnoAncestry reported to Peter Cooley was that his Y chromosome group was R1b. That is nice to know, but that is the most common haplogroup in Western Europe, so it does little to indicate the closeness of our relationship. Fortunately EthnoAncestry also reported the values for 25 SNP markers on his Y chromosome, so we have his haplotype and can compare it to others and establish genetic distances among them.

I combined his results with other results which help in interpreting his y-DNA profile. The five profiles, or haplotypes, which I have included are as follows:Modal R1b lists the most frequent values (i.e. the modal values) for men in Haplogroup R1b, which is the most common genetic group in Western Europe, and includes our Cooley family.Irish Modal are the most frequent values for Irish males that have been studied by a genetic genealogy lab at Trinity College, Dublin.Cooley Modal are the values for Cooley men known to be descendents of Benjamin Cooley.William Cooley lists the values for my DNA profile.Peter Cooley shows the new results for our Cooley volunteer from England.

So for example, the marker DYS 19 has a modal value of 14 for men known to be in Haplogroup R1b and for Irish men in the Trinity study. However, the Cooley modal value, and the value for the two Cooley men listed, have a value of 15. What puts this comparison in perspective is the fact that only about 6% of men who are known to be in Haplogroup R1b have a value of 15, most have a value of 14 on that marker. So those relative frequencies help to indicate on which markers the Cooley profile is rather unusual, at least among men in Western Europe. On marker 385a the Cooleys have a value of 10, but only about 3% of those in the R1b haplogroup have a value of 10, most have a value of 11. [Whit Athey reports these relative frequencies in the Journal of Genetic Genealogy.]

The full set results for these five haplotypes are reported in an Excel spreadsheet that can be obtained from me. (coolbill2@comcast.net) (Cooley DNA data.xls). What is particularly notable is the fact that Peter and William have identical values on all of the 16 markers that are available for both of us. This means that we probably have a common ancestor within the past 500 years, so now we need to figure out who that might be, and for that we need to turn to good old fashioned genealogy (dusty church records, for example).

Fortunately Peter Cooley is actively working on who that common ancestor might be. He has established that his Cooley line definitely goes back to Nehemiah Cooley, who was born in Little Gaddesden in 1750. He has also found that there was a Nehemiah Cooley born in Tring in 1685. What we need to do now is try to “connect the dots”, finding links between his Cooley line and our Benjamin line. All that DNA can tell us is that the chances are excellent that such a link exists. The Cooley Family Association of America is working with Peter to find such links.